Distribution Notes:

Throughout the mainland Neotropics, from Guatemala to Brazil and Bolivia. In Costa Rica: throughout the country in wet forest areas, to 1500m elevation in Monteverde.

Biology:

This species forms very large colonies. Nests may fill large rotten stumps or rotten logs (figures below). Often tell-tale piles of sawdust surround such nests, from workers excavating the interior. Workers are aggressive, and forage day or night. Large numbers of minor and major workers may be observed swarming out from nests and retrieving live insect prey, with a behavior reminiscent of army ants. Kugler (1979) has termed this "gang-pulling." Workers also have an enlarged pygidial gland that segretes a noxious gummy substance used in defense (Kugler 1979). Workers tend Homoptera and visit extrafloral nectar sources. Colonies may build scattered carton shelters on low vegetation and tend membracids and other Homoptera beneath them. Workers may aggressively defend extrafloral nectar sources (e.g. Passiflora shoots), driving away herbivores and other ants. Colonies use carton construction to form baffles in rotten wood, and galleries running up tree trunks. At Rara Avis, workers were observed tending large riodinid larvae under carton galleries.

Founding queens are found under loose bark of dead wood, in dead branches, and very commonly under epiphyte mats on recently fallen trees.

In Penas Blancas, Longino observed an interaction with phorid flies. Workers were streaming up a tree trunk. Phorids were hovering above. One landed on the head of a soldier. Afterwards, workers grabbed the soldier by the legs and slowly began to drag it down the trunk.

Notes:

biconstricta is a complex lineage with many infraspecific taxa in the taxonomic literature. Four of these have type localities in Costa Rica:biconstricta surda Forel 1912:222biconstricta bicolor Emery 1890:50biconstricta bicolor regina (unavailable quadrinomial)biconstricta rubicunda Emery 1890:50Wilson (2003) synonymized them all under biconstricta.

In Costa Rica, specimens from the southern Pacific lowlands are light orange. In Monteverde, they are two-toned, with light orange head and mesosoma, and somewhat darker gaster. On the Atlantic slope they are brown to dark brown. The transition can be sharp: specimens of the two-toned Monteverde form are known from open areas in and around Monteverde, on the Pacific slope west of the cloud forest that covers the continental divide; the dark brown form is common in the Penas Blancas Valley, about 5km east of Monteverde on the Atlantic slope. There is also variation in sculpture, but it does not show geographic patterns and varies within populations.

I have examined the types of all the above listed forms that are available nomenclaturally. What I have regarded here as the single species biconstrictaHNS is highly variable in details of size, sculpturing, and color, both locally and geographically, with general and overlapping intergradation. Closer studies with more material may well reveal biconstrictaHNS to be a complex of sibling species, to which at least some of the names will apply, but for the time being I have chosen the more conservative arrangement, that is, recognition of a single, very variable species.

types Naturhist. Mus. Wien.

Etymology L biconstrictaHNS, constricted (pinched) twice, once in front of the mesonotum and once behind it. Diagnosis A member of the biconstrictaHNS group distinguished as follows.

Range Widespread and locally abundant, occurring mostly in tropical moist forests from Guatemala to Brazil and Bolivia; present in Trinidad but absent from Tobago and the rest of the West Indies. Ranges to at least 1500 m in Costa Rica and to 2500 m in Colombia.

Biology P. biconstrictaHNS is a conspicuous ant in much of the tropical forests of the New World. It forms large colonies, with populations possibly in the tens of thousands, that nest in rotting logs and stumps on the forest floor. John T. Longino (1997) reports that in Costa Rica, "Workers are aggressive, and forage day or night. Large numbers of minor and major workers may be observed swarming out from nests and retrieving live insect prey, with a behavior reminiscent of army ants. Workers also tend Homoptera, and visit extrafloral nectar sources. Colonies may build scattered carton shelters on low vegetation, and tend membracids and other Homoptera beneath them. Workers may aggressively defend extrafloral nectar sources (e.g. Passiflora shoots), driving away herbivores and other ants. Colonies use carton construction to form baffles in rotten wood, and galleries running up tree trunks. At Rara Avis, workers were observed tending large riodinid larvae under carton galleries. Founding queens are found under loose bark of dead wood, in dead branches, and very commonly under epiphyte mats on recently fallen trees."

Charles Kugler (1979d) has described the capture of live insect prey by "gang-pulling, and the hypertrophial pygidial glands, which secrete a viscous gumming agent and irritant when smeared on enemies. Another behavior unusual for PheidoleHNS is the lifting of the gaster toward the enemy, making release of the toxin material more effective. Alarm pheromones also emanate from the same gland."

Specimen Habitat Summary

Found most commonly in these habitats: 42 times found in tropical wet forest, 14 times found in montane wet forest, 17 times found in cloud forest, 22 times found in 2º wet forest, 17 times found in wet forest, 14 times found in montane rainforest, 12 times found in mesophil forest, 15 times found in ridgetop cloud forest, 17 times found in oak cloud forest, 10 times found in cloud forest, on steep slope, probably old 2nd growth, near pasture, ...

Found most commonly in these microhabitats: 95 times at bait, 54 times ex sifted leaf litter, 22 times beating vegetation, 2 times in clearing, 7 times beating veg., 3 times foragers, 4 times on low vegetation, 2 times general collecting, 3 times under epiphytes, 3 times at baits, 4 times ex sifted litter, rotten wood, ...

Collected most commonly using these methods: 99 times Baiting, 61 times search, 31 times Beating, 29 times MiniWinkler, 18 times MaxiWinkler, 12 times Winkler, 7 times Ground forager, 4 times bait, 4 times Sweeping, 4 times Ground nest, 3 times hand collected, ...

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